1. Field of the Invention
The invention relates to an application of a halftone image processing technique, and more particularly to a method for optimizing class matrix and diffusion weighting used in a dot diffusion process of the halftone image processing technique and a system thereof.
2. Description of Related Art
A halftone image processing technique renders a continuous-tone image with fewer levels of color tones. Generally speaking, the halftone image processing technique has been widely applied in image output devices limited by output color levels. Printers, for example, can only output black by dotting and can output white by not dotting. Therefore, a halftone adjustment technique is needed to control the density variation of the black and white tones, so as to generate halftone images capable of simulating grayscale image effects. In more detail, since the human eye possesses effects of an optical low pass filter (OLPF), therefore outside of a distance, halftone images would appear to the human eye the visual effects similar to grayscale images.
Among halftone image processing techniques, the dot diffusion process is a well known method for generating halftone images. In short, the dot diffusion process uses a class matrix and a plurality of diffusion weightings in the diffusion regions to process the image in parallel. It is not hard to imagine that the quality of the class matrix and the diffusion weightings significantly impact the quality of the halftone images.